202 PROCEEDINGS OP THE AMERICAN ACADEMY 



I. 1.5136 grm. of the air-dried salt lost, at 125°, 0.2422 grra. H 2 0. 



II. 1.7684 grm. of the air-dried salt lost, at 160°, 0.2855 grm. H 2 0. 



III. 2.5118 grm. of the air-dried salt lost, at 180°, 0.4013 grm. H 2 0. 



Calculated for Found. 



BaC 6 Br,S0 6 . 5 H 2 0. I. II. III. 



H 2 15 65 16.01 16.14 15.97 



I. 0.5378 grm. of the salt dried at 125° gave 0.2575 grm. BaS0 4 . 



II. 0.4688 grm. of the salt dried at 180° gave 0.2243 grm. BaS0 4 . 



III. 0.5317 grm. of the salt dried at 180° gave 0.2550 grm. BaS0 4 . 



Calculated for Found. 



BaC 5 Br 2 S0 6 I. II. III. 



Ba 28.25 28.15 28.13 28.19 



The solubility of the salt in cold water we determined in the usual 

 way. 



I. 10.9011 grm. of the solution saturated at 20° gave 0.2170 grm. 

 BaS0 4 . 

 II. 11.9609 grm. of the solution saturated at 20° gave 0.2398 grm. 

 BaS0 4 . 



The solution saturated at 20°, therefore, contained the following 

 percentages of the anhydrous salt: — 



i. n. 



4.14 4.17 



When an aqueous solution of the barium salt is evaporated at 100°, 

 small clear prisms separate, which contain less water than the salt just 

 described. We found it impossible to prepare this salt satisfactorily 

 for analysis, siuce it at once took up water in the cold. A preparation 

 which was removed from the hot solution and immediately dried by 

 pressure with filter paper gave on analysis the following results : — 



I. 1.6161 grm. of the salt lost, at 140°, 0.1767 grm. H a O. 

 II. 0.6265 grm. of the salt gave 0.2665 grm. BaS0 4 . 



Plumbic Py-Dibrom-b-Sulphopyromucate, PbC 5 Br 2 S0 6 . 4 H 2 0. — 

 The lead salt is readily soluble in hot water, more sparingly in cold, 

 and crystallizes in fine felted needles, which are permanent in the air, 

 but effloresce over sulphuric acid. 



